Working horses in summer heat creates some significant welfare issues with consequences as severe as death. Research has provided some very valuable information but despite this there are still many myths and misconceptions. It isn’t only upper level performance/racing horses that are at risk. Serious dehydration and overheating can happen to any horse, especially with some of the misinformation out there.
“Never let a hot horse drink all they want, or drink cold water.”
Read more here at Horse Collaborative